1. Field of the Invention
This invention relates to a method for producing pulps, and more specifically, to a method for producing pulps for various uses by previously fiberizing wood chips used as the original material and then degrading lignin contained in the fiberized wood, at various degree of lignin-degradation, by a microorganism having a high lignin-degrading activity and a low fiber-degrading activity, a culture solution of the microorganism or a substance obtained by treating the solution.
This invention enables energy-saving and high-yield production of pulps and therefore plays an important role in industrial application using a so-called lignocellulose-system biomass.
2. Description of the Prior Art
Pulps are mainly produced from wood and are roughly divided into chemical pulps which do not contain lignin almost entirely, semichemical pulps which contain a small amount of lignin and mechanical pulps which have compositions almost similar to that of wood and contain a large amount of lignin. Chemical pulps and semichemical pulps are produced by decomposing lignin contained in wood, therefore, lignin-degradation by a microorganism enables pulps having nearly the same composition as chemical and semichemical pulps to be produced.
However, as any microorganism having a high lignin-degrading activity and a low fiber-degrading activity has not been isolated up to now, it is the present situation that "it seems impossible to produce a pulp like a chemical pulp from which lignin has sufficiently been decomposed" (Hisao Ishikawa: Wood Pulp Technology Times, 5, 1-10 (1983)).